Coating composition, it's coating layer, antireflection coating, antireflection film, image display and intermediate product

Abstract

The present invention provides an application material capable of forming a thin layer of high quality having controlled refractive index, a coating layer formed by using said application material, an antireflection coating using said coating layer, an antireflection film and image display to which said antireflection coating is applied. A coating layer formed from a coating composition comprising (1) rutile type titanium oxide coated with an inorganic compound decreasing or eliminating a photocatalyst activity and an organic compound and / or organometal compound having an anionic polar group, and having a primary particle size in the range from 0.01 to 0.1 μm, (2) a binder component having an ionizing radiation-curing property, (3) a dispersing agent having an anionic polar group, and (4) an organic solvent is suitable for forming a light transmission layer constituting a single-layer type or multi-layer type antireflection coating 17, partucularly, a middle refractive index layer 18, high refracive index layer 19 or hard coat layer 16 having high refractive index (FIG. 2).

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This application claims the priority of Japanese patent application Serial No's. 2001-006325, filed on Jan. 15, 2001, 2001-220330, filed on Jul. 19, 2001 and 2001-220332, filed on Jul. 19, 2001.TECHNICAL FIELD[0002]The present invention relates to a coating composition excellent in dispersibility, dispersion stability and coating aptitude, and an optical thin layer formed by using this coating composition. More specifically, the present invention relates to a coating composition suitable for forming an optical thin layer having controlled refractive index, typically, a layer constituting an antireflection coating with which the surface of a display such as LCD, CRT and the like is coated, particularly, a high refractive index hard coat layer having an function as a supporting layer for a middle to high refractive index layer and a function as a high refractive index layer, together, and a middle to high refractive index layer having excell...

AI Technical Summary

Benefits of technology

[0029]The coating composition of the present invention can easily control the refractive index of a coating layer since the composition comprises ritile type titanium oxide having high refractive index. In the coating composition of the present invention, a dispersing agent having an anionic polar group is mixed with the titanium oxide, for dispersing the titanium oxide uniformly and stably. Further, in the coating composition of the present invention, the titanium oxide is coated with an inorganic compound, and additionally, coated with an organic compound and / or organometal compound having an anionic polar group. By surface-treating the titanium oxide with an organic compound or organometal compound to impart affinity to a binder component and the like, dispersibility of the titanium oxide in a coating liquid can be further improved.

[0061]Further, according to the present invention, it is possible that, when a layer having a layer thickness of 0.2 to 20 μm after curing is formed, the refractive index is controlled in the range from 1.55 to 2.30, and a haze value according to JIS-K 7361-1 is controlled to the same value as in the case of using only the above-mentioned substrate or suppressed so that a difference from the haze value in the case of using only the above-mentioned substrate is within 10%, thus a high refractive index hard coat layer can also be formed.

Problems solved by technology

In the case of the gas phase method, it is possible to form a high refractive index layer and a middle refractive index layer having high functions and high quality, however, there are problems that precise control of atmosphere in a high vacuum system is necessary, a special heating apparatus or ion generating-accelerating apparatus is necessary, and for this reason, a production apparatus is complicated and its size increases, leading necessarily to increase in production cost.

Further, it is difficult to enlarge the area of a thin layer of a high refractive index layer and middle refractive index layer or to form a thin layer having uniform thickness on the surface of a film having complicated form.

On the other hand, in the case of the spray method among application methods, there are problems that an efficiency to utilize a coating liquid is poor, and control of layer forming conditions is difficult, and the like.

In the case of a roll coat method, gravure coat method, slide coat method, immersion method, screen printing method and the like, an efficiency to utilize layer formation raw materials is good, and merits are present in large scale production and equipment cost, however, there is generally a problem that a high refractive index layer and middle refractive index layer obtained by an application method are poor in functions and quality in comparison with those obtained by a gas phase method.

When solid components of a coating liquid aggregate, haze of the resulting coating layer deteriorates.

However, since ultra-fine particles have increases surface area, a large amount of dispersing agent is necessary for dispersing ultra-fine particles uniformly in a coating liquid and for stabilizing ultra-fine particles so that they can stand storage for a long period of time.

When a large amount dispersing agent is mixed in a coating liquid, the dispersing agent is present in large amount also in a coating layer formed using the above-mentioned coating liquid, and the dispersing agent prevents curing of binder components, and significantly lowers the strength of the coating layer.

Additionally, though the hard coat layer is required to have high hardness, a dispersing agent has a nature of preventing curing of a binder of a coating layer as described above, therefore, the amount of a dispersing agent which can be mixed in a coating liquid for a hard coat layer is limited further than in the case of a coating liquid for a middle to high refractive index layer.

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